12
This conformation of cis-2-butene has Cs symmetry
 6   0.030847946   1.474842724  -2.459731033
 6   0.030847833   1.474842724  -0.928731015
 6   1.184367609   1.474842724  -0.262745829
 1  -0.918315897   1.474842724  -0.380730858
 6   2.510252686   1.474842724  -1.028245548
 1   1.184367078   1.474842724   0.833254155
 1   3.343300145   1.474842724  -0.316032165
 1   2.568310759   2.369722900  -1.658352423
 1   2.568310759   0.579962549  -1.658352423
 1   1.064166492   1.474842724  -2.825064783
 1  -0.485811585   2.369722900  -2.825064151
 1  -0.485811585   0.579962549  -2.825064151
